Dehydrogenation characteristics of LiAlH4 improved by in-situ formed catalysts

摘要

The hydrogen storage properties and catalytic mechanism of FeCl2-doped LiAlH4 were investigated in minute details.LiAlH4-2 mol％ FeCl2 samples start to release hydrogen at 76 ℃,which is 64 ℃ lower than that of as-received LiAlH4.Isothermal desorption measurements show that the 2 mol％ FeCl2-doped sample releases 7.0 wt％ of hydrogen within 17 min at 250 ℃.At lower temperatures of 110 ℃ and 80 ℃,the sample can release 4.4 wt％ and 3 wt％ of hydrogen,respectively.The apparent activation energy of LiAlH42 mol％ FeCl2 samples for R2 is 105.02 kJ/mol,which is 67 kJ/mol lower than that of pure LiAlH4.The reaction between LiAlH4 and FeCl2 during ball milling was found by analyzing the X-ray diffraction results,and Fe-Al particles formed in-situ from the reaction act as the real catalyst for the dehydrogenation of LiAlH4.